Add keycloak and idl for local development

Description

• Aim is to ease local development in mocking/including helmholtz aai (using keycloak and idl in the docker compose setup

Task

• update nginx to use http instead of https
• include keycloak
  • document the setup
  • document usage
• include idl
  • using https://codebase.helmholtz.cloud/hub-terra/sms/gfz-idl
  • document/link setup
  • document usage
• Update setup in Readme.md